The present invention relates to a handler for measuring the electric characteristics of a semiconductor device and, more particularly, to control of an package temperature of a semiconductor device having a semiconductor chip generating a large amount of heat, and to control of a test environment.
In a recent semiconductor technique, a test handler for continuously measuring the characteristics of a large number of semiconductor devices is used.
In this test handler, the package temperature of a semiconductor device transits changes as described follows according to a procedure for measuring electric characteristics, as shown in FIG. 3.
First, depending on conditions of xe2x80x9cmagnitude of passing currentxe2x80x9d, xe2x80x9clevel of applied voltagexe2x80x9d, and xe2x80x9clength of application timexe2x80x9d in Test 1, a set temperature increases with progress of time.
Second, the set temperature increases with progress of time depending on the conditions in Test 2.
Third, the set temperature decreases with progress of time depending on the conditions in Test 3.
Fourth, upon completion of excitation, the set temperature decreases to the temperature of a temperature chamber.
Fifth, when a semiconductor device is removed from the temperature chamber, the set temperature decreases to a room temperature.
In this graph, the description is made on the assumption that the factors which increase package temperatures depending on the conditions in Tests 1, 2, and 3 satisfy the condition of Test 3 less than Test 1 less than Test 2.
For example, in a prior art in which an atmospheric temperature in the temperature chamber is controlled under the condition of 85xc2x0 C.xc2x13xc2x0 C., it is considered that a change in temperature (temperature difference xcex94TC1) shown in FIG. 3 occurs because a change in package temperature does not immediately cause a change in atmospheric temperature in the temperature chamber and because the function of a temperature control system for detecting the atmospheric temperature in the temperature chamber does not instantaneously respond to the change in package temperature.
In addition, FIG. 2 shows the package temperature of a semiconductor device when the electric characteristics are measured by the test handler of the prior art.
The package temperature of the semiconductor device changes as follows according to the procedure of measuring the electric characteristics.
First, after the package temperature increases to a set temperature obtained by heating in the temperature chamber, a measurement of electric characteristics is started.
Second, the electric characteristics are measured while conditions are sequentially changed to the conditions in Test 1, Test 2, and Test 3.
Third, since a self calorific value of a semiconductor device due to excitation is very small, the envelope temperature slightly changes.
Fourth, upon completion of excitation, the semiconductor device is conveyed out of the temperature chamber, and the package temperature decreases to a room temperature.
FIG. 8 shows typical characteristics of a semiconductor device. It is generally known that a characteristic X changes (from X1 to X2) as indicated by a quadratic curve A with a change in envelope temperature (from T1 to T2).
In the handler according to the prior art, the following problems are posed because the package temperature of a semiconductor device considerably changes.
First, the electric characteristic value of semiconductor device changes with a temperature by an increase in temperature caused by excitation.
Second, the degree of an increase in temperature changes depending on the magnitude of a passing current or the level of an applied voltage, and the electric characteristic value of the semiconductor device changes.
Third, the degree of an increase in temperature changes depending on the length of excitation time, and the electric characteristic value of the semiconductor device changes.
Fourth, when a plurality of electric characteristics are measured in series with each other according to a program, the degree of an increase in temperature (for example, xcex94TC1 in FIG. 3) changes depending on a combination of the magnitude of a passing current and the length of excitation time (for example, Test 1, Test 2, and Test 3 in FIG. 3), and the electric characteristic value of the semiconductor device changes.
Fifth, in a state wherein the temperature of the semiconductor device continuously changes because of the above factors which change the characteristic values, as indicated by a characteristic X in FIG. 8, the electric characteristic value is not easily specified.
Since the above problems are posed, in a test handler for a semiconductor device having a large amount of heat generation, the electric characteristic value is not easily specified because of a change in electric characteristic caused by the change in temperature of the semiconductor device in the prior art in which xe2x80x9cthe atmospheric temperature in the temperature chamber is detected to control the temperature in the temperature chamberxe2x80x9d. For this reason, the test handler of the prior art cannot be used.
More specifically, since the temperature of the semiconductor device is measured by the atmospheric temperature in the temperature chamber, the measurement cannot quickly respond to the change in temperature of the semiconductor device itself. For this reason, it is difficult to precisely specify an electric characteristic value depending on the present temperature.
It is an object of the present invention to measure a surface temperature of a semiconductor device to realize precise measurement of electric characteristics depending on the surface temperature.
According to the present invention, there is provided a test handler for a semiconductor device comprising: a temperature chamber for storing a semiconductor device sealed in a package; detection means, arranged in the temperature chamber, for detecting a surface temperature of the package of the semiconductor device; temperature control means for performing temperature control of the temperature chamber to set the temperature of the package detected by the detection means at a predetermined temperature; and measurement means for applying a predetermined potential to the semiconductor device to measure electric characteristics.
According to the present invention, with the above arrangement, since the temperature of a semiconductor device is conventionally measured by only the atmospheric temperature of the temperature chamber, a precise electric characteristic value depending on the present temperature cannot be easily specified. According to the present invention, since the surface temperature of the device is directly measured, electric characteristics can be very precisely measured.
According to the present invention, there is provided a test handler for a semiconductor device comprising: a temperature chamber for storing a semiconductor device sealed in a package; holding means, arranged in the temperature chamber, for holding the semiconductor device; pressing means for pressing a temperature sensor onto a surface of the package of the temperature chamber held by the holding means by using a spring; detection means for detecting a surface temperature of the package of the semiconductor device by the temperature sensor pressed onto the surface of the package; temperature control means for performing temperature control of the temperature chamber to set the temperature of the package detected by the detection means at a predetermined temperature; and measurement means for applying a predetermined potential to the semiconductor device to measure electric characteristics when the temperature of the package becomes the predetermined temperature.
According to the present invention, when the temperature sensor is pressed onto the semiconductor device by using the spring, a more precise surface temperature can be measured, and precise measurement of the electric characteristics based on reliable temperature measurement can be realized.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.